1. Field of the Invention
The present invention relates in general to an arrangement and method for heat treating a workpiece in motion with a beam of energy or radiation and, more particularly, pertains to an arrangement and method for utilizing a collimated laser beam to sequentially spot weld each of a plurality of moving workpieces which are successively conveyed through the laser beam.
2. Discussion of the Prior Art
Charschan et al. U.S. Pat. No. 4,151,014 discloses a laser annealing arrangement in which a predetermined segment of a metallic workpiece is annealed to a controlled degree of temper by irradiating that portion with a pulsed laser beam. The intensity of the beam and/or the pulse width thereof is regulated so as to impart the controlled degree of temper to the pertinent portion of the workpiece. The pulsed laser allows heat to be selectively applied to a particular portion of the workpiece in a manner which will rapidly elevate that portion to an annealing temperature. The prior art arrangement results in controlled annealing of one small portion of the workpiece with only negligible lateral conduction of heat into encompassing or adjacent areas of the workpiece. In the arrangement, a pulse from the laser is directed through a focusing lens onto the area of the workpiece which is to be annealed. Thus, Charschan et al. is directed to an annealing arrangement wherein all components of the system, including the workpiece, remain stationary throughout the annealing operation and, presumably after completion thereof, the selectively annealed stationary workpiece is removed and then replaced by another workpiece for a repetition of the annealing operation.
Ralston et al. U.S. Pat. No 3,663,301 discloses an alkaline dry cell primary battery which incorporates a construction in which a spot weld is provided between an external circular anode plate and an internal anode collector so as to form a fixed connection between these elements. Various types of welding equipment have heretofore been utilized to perform this spot welding operation, however, all of these prior art arrangements necessitated the battery to be maintained stationary during the performance of the welding operation. The need for the stationary positioning of the battery during the spot welding operation imparted a limitation to these prior welding arrangements in that it resulted in a relatively time-consuming and expensive welding operation. The usual economic goal of achieving low cost mass production and developing a higher rate of production output for each unit of time has always been a pressing and desirable factor in the development of cells of this type, inasmuch as primary batteries are essentially "throw-away" products which are electrically depleted during normal usage and are discarded after the chemical components therein are essentially completed coverted into an electrically inactive condition. Furthermore, the evolution and development of alkaline dry cells has resulted in the achievement of greatly improved performance and power output in that type of cell which has led to the utilization thereof in many fields of application wherein primary electrical chemical cells had heretofore generally not been in common usage.
Consequently, automating to a greater degree the spot welding operation which is performed between the internal anode collector and the exterior element forming one terminal of this cell while conveying the cell through its manufacturing apparatus represents a significant improvement in the state of the art of producing alkaline dry cell primary batteries, and facilitates the production of such batteries in a more cost effective and time saving manner.